How Does Physical Activity Enhance the Subjective Well-Being of University Students? A Chain Mediation of Cognitive Reappraisal and Resilience

Background: Regular physical activity is an effective means to enhance university students’ subjective well-being. However, current research needs to understand how physical activity enhances the subjective well-being of Chinese university students. Therefore, the study investigated the mechanism of physical activity’s impact on university students’ subjective well-being and the mediating roles of cognitive reappraisal and resilience in this mechanism. Methods: The physical activity scale, subjective well-being scale, cognitive reappraisal scale and resilience scale were used to investigate 1350 university students, and the relationship between physical activity, cognitive reappraisal, resilience and university students’ subjective well-being was verified through correlation analysis, regression analysis and a Bootstrap method. Results: (1) There is a significant positive correlation between physical activity, cognitive reappraisal, resilience and university students’ subjective well-being (p < 0.01); (2) physical activity, cognitive reappraisal and resilience all have a significant positive effects on university students’ subjective well-being (p < 0.01); (3) cognitive reappraisal and resilience have significant mediating roles in the process of physical activity affecting university students’ well-being, with mediating-effect values of 0.052 and 0.285; (4) the chain-mediating role of cognitive reappraisal and resilience in the process of physical activity affecting university students’ well-being is significant, with the chain-mediating effect value of 0.062. Conclusion: Promoting university students’ participation in physical activity not only directly enhances university students’ subjective well-being but also indirectly improves university students’ subjective well-being through cognitive reappraisal and resilience.


Introduction
University students are a particular social group in the critical stage of transition from adolescence to adulthood, carrying the double pressure of academic learning and social practice, and are more prone to mental health problems such as anxiety, insomnia, and depression [1,2].According to the 2015 American University Health Assessment, 56.9% of university students were highly anxious, and 34.5% tended toward depression.Levels of mental health problems among university students have continued to rise compared to in 2008 and 2011 [3].With the development of positive psychology, many scholars have realised that improving subjective well-being is a crucial way to promote people's mental health [4].Subjective well-being (SWB) refers to people's overall emotional and cognitive evaluation of their quality of life, usually including emotional experience and cognitive evaluation [5,6].Subjective well-being refers to the overall affective and cognitive evaluation of people's quality of life.In a sense, it is not what happens that determines Behav.Sci.2024, 14, 164 2 of 15 whether people are happy, but rather what kind of emotional and cognitive interpretations and processing they make of what happens.Studies have shown that subjective well-being positively impacts university students' physical and mental health, which can help them relieve psychological stress, improve life satisfaction, stimulate positive emotions, and reduce depression, anxiety, and other adverse events [7,8].However, the low subjective well-being among Chinese university students has caused many problems for their healthy growth and psychological health [9].Although some scholars have demonstrated the relationship between physical activity and subjective well-being among university students, there is a lack of empirical research on the subjective well-being of Chinese university students, as most studies are qualitative.Considering the unique background of China's cultural and social environment and the urgency of the problem, it is necessary to further test the influence mechanism of physical activity on Chinese university students' subjective well-being based on previous studies to provide specific theoretical support for the enhancement of Chinese university students' subjective well-being.
Physical activity (PA) is an activity in which there is an increase in the body's energy expenditure due to the contraction of skeletal muscles [10].Physical activity can bring many benefits, such as improving cardiovascular function, accelerating bone and muscle growth, reducing the prevalence of various diseases, and helping people to maintain a healthy body [11].At the same time, physical activity can also help people release psychological stress, relieve anxiety and enhance life satisfaction and happiness, which is conducive to the development of psychological health [12].Among them, enhancing subjective well-being is one of the essential benefits of physical activity.Research has shown a close relationship between physical activity and people's subjective well-being, and physical activity significantly positively affects people's subjective well-being [13][14][15].Appropriate physical activity can help university students stimulate positive psychology and emotions, enhance life pleasure and satisfaction, and improve university students' emotional experience and cognitive evaluation of their quality of life, thus enhancing people's subjective well-being [4].In addition, physical activity can also help people release internal pressure, relieve anxiety, and reduce the emergence of depression, which also helps to enhance people's perceived subjective well-being [16].However, some scholars have found that the effects of different exercise intensities on people's subjective well-being vary, and in particular, moderate-intensity physical activity has the best effect on people's subjective well-being [17].Moreover, evidence that physical activity affects people's subjective well-being can be inferred from genetic and cognitive neuroscience studies, but the physiological mechanisms need to be further clarified [18].In summary, Hypothesis 1 is proposed: physical activity positively affects university students' subjective well-being.
Cognitive reappraisal (CR) is a positive conditioning strategy to change emotional experiences by reinterpreting the meaning of the stimulus environment or stressful situation [19,20].In other words, by re-selecting the focus of attention on the current stimulus, the brain perceives and interprets the event differently.Physical activity can provide a diverse range of emotional stimulus scenarios, including the frustration of losing a game, the gruelling nature of athletic training, and the joy of success in a game; these emotional events can help people improve their emotional regulation inertia, which can in turn influence individuals' appraisals of the state and quality of their life [21].Research has shown that regular physical activity can effectively reduce the incidence of depression and anxiety among university students, continuously optimise and optimise their emotional experience, and promote a more effective cognitive reappraisal of adverse emotional events [22][23][24].For example, university students' participation in physical activity can release inner pressure, relieve anxiety, and promote mental health, which to a certain extent can alleviate internalised problems such as depression, anxiety and irritability and help university students to correctly understand adverse events and emotions and choose more positive cognitive reappraisals.In addition, cognitive reappraisal can promote a more positive attitude towards the events that happened and then promote higher subjective well-being [25].According to Gross et al. (2003), cognitive reappraisal early in the emo-tional process reduces the perception of emotional events and negative emotions and has a "defensive" effect during this process, thus contributing to higher subjective well-being [20].Meanwhile, individuals who use cognitive reappraisal strategies tend to be more satisfied with their lives, have more positive interpersonal relationships, have more explicit life goals, and show fewer symptoms of depression [26].St-Louis et al. (2020) examined the effects of five emotion-regulation strategies on subjective well-being and found that only cognitive reappraisal was positively related to subjective well-being [27].Cognitive reappraisal may mediate between university students' physical activity and subjective well-being.However, there needs to be more direct evidence.Accordingly, Hypothesis 2 is proposed: cognitive reappraisal mediates the relationship between physical activity and university students' subjective well-being.
Resilience is an individual's effective adaptation to stressful situations such as misfortune, adversity or frustration, which allows people to maintain normal psychological and physiological functioning even in stressful situations [28].Research has shown a close relationship between physical activity and university students' resilience [29,30].Physical activity has the characteristics of groups, education and openness, which can create a good space and conditions for developing university students' resilience.For example, university students need to face some pressure and adversity in the process of participating in physical activity, which can help to increase the ability of university students to cope with difficulties and pressure physically and mentally, improve the physiological and psychological state, and improve the adaptability of destructive emotions, and ultimately help university students to improve their resilience [31].In addition, resilience as an essential psychological resource also produces positive psychological benefits, such as subjective well-being and life satisfaction.Studies have shown that university students' resilience is closely related to subjective well-being and has a positive impact on university students' subjective well-being [32,33].Generally speaking, university students with better resilience will actively cope with and solve the problems and measures encountered in sports, maintain a good psychological state and positive emotions, and ultimately show higher subjective well-being [34].Resilience has been discussed as a mediating variable in many psychological factor studies.Also, it plays a mediating role in the relationship between physical activity, mental health and subjective well-being [35,36].The study concluded that university students' regular participation in physical activity can improve their resilience and keep them psychologically stable in stressful and frustrating situations.Therefore, they will make more positive evaluations of their life status and also be able to maintain a positive emotional experience.Accordingly, Hypothesis 3 is proposed: resilience mediates the relationship between physical activity and university students' subjective well-being.
In addition, research has shown a strong relationship between cognitive reappraisal and resilience, and cognitive reappraisal positively impacts resilience [37,38].Verdolini et al. (2021) suggested that cognitive reappraisal is an essential factor influencing resilience, that the use of cognitive reappraisal strategies can change an individual's appraisal of a stressor, which in turn attenuates negative emotions, and that this adaptive emotional response process offers the possibility of increased psychological resilience [39].Cognitive reappraisal training is a meaningful way to enhance psychological resilience, effectively improving an individual's adaptation to adverse situations and maintaining normal physiological and psychological states [40].Although there is no direct evidence of the relationship between physical activity, cognitive reappraisal, resilience and subjective well-being among Chinese university students, related studies have shown that cognitive reappraisal and resilience may have a chain-mediated effect in the process of physical activity, affecting subjective well-being.Therefore, the study suggests that there may be a chain-mediation path of "physical activity → cognitive reappraisal → resilience → subjective well-being", and that the intrinsic mechanism by which physical activity enhances university students' subjective well-being may be as follows: physical activity can promote the development of university students' cognitive reappraisal ability so that university students can effectively cope with and adapt to the pressure or stressful events in life and study, and maintain a stable state of mind, and then have a more positive evaluation of their quality of life, and ultimately maintain a higher sense of subjective well-being.Accordingly, Hypothesis 4 is proposed: cognitive reappraisal and resilience mediate the relationship between physical activity and university students' subjective well-being.
In summary, there is a close relationship between physical activity, cognitive reappraisal, mental toughness and university students' subjective well-being.Although related studies have revealed correlations among the four core variables, it is rare to find studies that actually construct chain-mediation models around the four core variables.By constructing a chain mediation model of the subjective well-being of university students, we can not only further reveal the complex mechanism of physical activity affecting university students' subjective well-being, but also provide a more theoretical basis for the promotion of university students' physical activity.

Procedure and Participants
A scale survey was conducted from September 2023 to November 2023 using a stratified whole cluster random sampling method among university students from six universities in five regions, including Beijing, Shanghai, Jiangsu, Zhejiang and Anhui.This study was conducted strictly with the 1964 Declaration of Helsinki and its subsequent amendments, while the Ethics Committee approved all methods used in this study.In addition, informed consent was obtained from all subjects before the start of the study.The scales were explained clearly to the subjects about the purpose, content and confidentiality before distribution and were completed independently with the subjects' consent.The scales were distributed online and offline, and 1496 scales were collected.Based on the exclusion criteria, such as regularity of filling in, consecutive omission, and timeout, 146 scales were excluded and 1350 valid scales were retained, with an effective recovery rate of 90.24%.Among the valid samples, there were 743 males and 607 females, with an average age of 20.43 years old, 1019 undergraduates and 331 postgraduates, mainly from the five regions of Beijing, Shanghai, Jiangsu, Zhejiang and Anhui, covering a variety of sports, such as basketball, football and badminton.Details of the participating university students are shown in Table 1.The Physical Activity Rating Scale measures an individual's level of physical activity in terms of intensity, duration and frequency of exercise [41].The scale is based on the following three dimensions.Exercise volume = intensity × time × frequency, and intensity and frequency are divided into five grades, each scoring 1-5 points, and time is scored 0-4 points from grades 1-5, with total scores ranging from 0-100.Total exercise was scored as follows: ≤19 as low exercise level, 20-42 as moderate, and ≥43 as high.After processing according to the calculation formula, the low exercise level was set as "1", the medium exercise level as "2", and the high exercise level as "3" for statistical analyses.In this study, the scale Cronbach's coefficient = 0.912, measurement model fit: χ 2 /df = 2.81, CFI = 0.905, TLI = 0.927, RMSEA = 0.066 and SRMR = 0.037, and the scale had good construct validity.

Subjective Well-Being Scale
We used a revision of the subjective well-being scale developed by Emmons et al. (1985), adapted for the Chinese physical activity scenario, including three dimensions of psychological emotions, satisfaction with the exercise effect, and satisfaction with the exercise relationship, with a total of 17 topics [42].A 7-point Likert scale ranged from "Strongly Disagree" to "Strongly Agree", with higher total scores representing higher subjective well-being.This study used the scale Cronbach's coefficient = 0.905, measurement model fit: χ 2 /def.= 2.97, CFI = 0.975, TLI = 0.955, RMSEA = 0.036, SRMR = 0.045, and the scale had good construct validity.

Cognitive Reappraisal Scale
We used the cognitive reappraisal scale from the Emotion Regulation Scale [20].The scale consists of 6 items, which were modified accordingly, considering university students' language acceptance and comprehension ability; when I want to feel less destructive emotions, I will try to change my thoughts.Using the Likert 5-point scale from "not at all (1)" to "completely ( 5)", the total score indicates the level of university students' use of cognitive reappraisal to regulate their emotions.In this study, the scale Cronbach's coefficient = 0.908, measurement model fit: χ 2 /df = 3.13, CFI = 0.935, TLI = 0.915, RMSEA = 0.056, SRMR = 0.035, and the scale had good structural validity.

Resilience Scale
A revision of the sport resilience scale was developed by Sheard et al. (2009) [43].The scale consists of three dimensions: confidence, assertiveness and control, with four items for each dimension and twelve items.The revised Chinese version of the scale has good reliability and operability, and the scale is scored using a five-point Likert scale, with scores ranging from "1" to "5", representing "not at all" to "not at all".A higher total score on the scale indicates a higher level of resilience of the individual in sports.In this study, the scale had a Cronbach's coefficient α of 0.880, a measurement model fit: χ 2 /df = 2.92, CFI = 0.973, TLI = 0.949, RMSEA = 0.064, and SRMR = 0.026, which gave good construct validity to the scale.

Statistical Methods
Using SPSS 25.0 and AMOS 25.0 software, the parameter estimates were calculated using the maximum likelihood method, and the following operations were carried out sequentially: (1) the reliability and validity of the scale were tested through the Cronbach coefficients and the fitted model indicators; (2) the data were standardised by using the Z standardisation method using the SPSS.25 software, and the difference between the value of each variable and its mean was divided by the variable's standard deviation.The mean value of each variable is 0, and the standard deviation is one after dimensionless quantification, thus eliminating the influence of the scale and order of magnitude.Then, correlation analysis and regression analysis were sequentially conducted to explore the relationship between physical activity, cognitive reappraisal, resilience, and a subjective well-being; (3) bias-corrected non-parametric percentage Bootstrap 95% confidence-interval estimation method was used to explore the mediating effects of cognitive reappraisal and resilience.

Common Method Bias
As the data obtained were mainly obtained through self-administered scales, the issue of common methodological bias may exist.For this reason, procedural control and Harman's one-way test were used to examine possible common methodological biases in administering the test.In terms of procedural control, (1) a well-established scale with good reliability and operability was chosen as the measurement tool; (2) a reverse question was added to each subscale to facilitate the screening of valid scales; (3) the scale was labelled as "for research use only" to emphasise the confidentiality and anonymity of the scale; and (4) on-site instruction and limited distribution were used to collect the data.For Harman's one-way test, all items in the scale were subjected to one-way unrotated exploratory factor analysis.A total of 35 factors with eigenvalues >1 were extracted, and the variance of factor 1 was 30.384% (<40%), which indicated that the standard method bias of the measurement was acceptable.

Descriptive Analyses, Correlation Analyses and Analyses of Variance for Core Variables
Descriptive and correlation analyses show (see Table 2) that the mean values of the scores of physical activity, cognitive reappraisal, resilience and subjective well-being are more significant than the median value, which indicates that the investigated group of university students has a better level of physical activity, cognitive reappraisal, resilience and subjective well-being; physical activity, cognitive reappraisal, resilience and subjective well-being have significant positive correlations (p < 0.01), with correlation coefficients r between 0.310-0.620,which provides some support for further hypothesis-model testing as well as mediation analysis.In order to examine the possible differential impact of demographic factors (gender, age, education and region) on the subjective well-being of university students, we conducted an independent samples t-test or ANOVA on the valid data (see Table 3).We found some differences in subjective well-being among university student groups of different genders, ages, educations and regions.Specifically, there is no significant difference between university student groups in terms of gender and region (p > 0.05), indicating that different genders and regions do not have a differential impact on university students' subjective well-being; there is a significant difference between university student groups in terms of age, qualifications and activity level (p < 0.05), indicating that different ages' qualifications and activity levels will have a differential impact on university students' subjective well-being, which provides a theoretical basis for subsequent statistical analysis.

Hypothetical Model Testing
In this study, we used the Process plug-in of the SPSS macro program prepared by Hayes, selected mode 6, and, after controlling for gender, age, education and region, we used physical activity as the independent variable, subjective well-being as the dependent variable and cognitive reappraisal and resilience as the mediator variables to test the effects of cognitive reappraisal and resilience in the process of physical activity in the process of affecting university students' subjective well-being as well as the chain-mediation effect.According to the results of regression analyses (see Table 4 and Figure 1), firstly, physical activity significantly and positively predicted subjective well-being (β = 0.502, p < 0.01) and cognitive reappraisal (β = 0.748, p < 0.01); secondly, physical activity (β = 0.574, p < 0.01) and cognitive reappraisal (β = 0.167, p < 0.01) significantly and positively predicted resilience; and finally, when physical activity, cognitive reappraisal and resilience were entered into the regression equation simultaneously, physical activity (β = 0.104, p < 0.01), cognitive reappraisal (β = 0.069, p < 0.01) and resilience (β = 0.496, p < 0.01) all significantly and positively predicted university students' subjective well-being.These results suggest that cognitive reappraisal and resilience have a significant mediating role and a chainmediating role in the physical activity process influencing university students' subjective well-being.

Hypothetical Model Testing
In this study, we used the Process plug-in of the SPSS macro program prepared by Hayes, selected mode 6, and, after controlling for gender, age, education and region, we used physical activity as the independent variable, subjective well-being as the dependent variable and cognitive reappraisal and resilience as the mediator variables to test the effects of cognitive reappraisal and resilience in the process of physical activity in the process of affecting university students' subjective well-being as well as the chain-mediation effect.According to the results of regression analyses (see Table 4 and Figure 1), firstly, physical activity significantly and positively predicted subjective well-being (β = 0.502, p < 0.01) and cognitive reappraisal (β = 0.748, p < 0.01); secondly, physical activity (β = 0.574, p < 0.01) and cognitive reappraisal (β = 0.167, p < 0.01) significantly and positively predicted resilience; and finally, when physical activity, cognitive reappraisal and resilience were entered into the regression equation simultaneously, physical activity (β = 0.104, p < 0.01), cognitive reappraisal (β = 0.069, p < 0.01) and resilience (β = 0.496, p < 0.01) all significantly and positively predicted university students' subjective well-being.These results suggest that cognitive reappraisal and resilience have a significant mediating role and a chain-mediating role in the physical activity process influencing university students' subjective well-being.To further understand the chained mediation effects of cognitive reappraisal and resilience, the constructed mediation model continued to be tested using the percentile Bootstrap method, the most widely used method for directly testing the product of coefficients, which belongs to a replicated sampling method.In contrast, the Bootstrap method can be applied to medium and small samples and various mediation-effect models, and various statistical software commonly used today can carry out Bootstrap calculations.In addition, the Bootstrap method is superior to the product-distribution method, which is superior to the Sobel test, in which the bias-corrected percentile Bootstrap method provides the most accurate estimate of confidence intervals and has the highest statistical efficacy [44].Specifically, the Bootstrap method obtains Bootstrap confidence interval estimates for ab by continuously drawing Bootstrap samples and calculating estimates of a and b.If the interval estimate does not include zero, the mediation effect is significant; if the interval estimate includes zero, the mediation effect does not exist [45].The results of the mediated effects showed (see Table 5) that the Bootstrap 95% confidence intervals for the total indirect effects arising from physical activity and subjective well-being did not include a value of 0 (BootLLCI = 0.426, BootULCI = 0.578), suggesting that cognitive reappraisal and resilience mediated significant effects between physical activity and subjective well-being, To further understand the chained mediation effects of cognitive reappraisal and resilience, the constructed mediation model continued to be tested using the percentile Bootstrap method, the most widely used method for directly testing the product of coefficients, which belongs to a replicated sampling method.In contrast, the Bootstrap method can be applied to medium and small samples and various mediation-effect models, and various statistical software commonly used today can carry out Bootstrap calculations.In addition, the Bootstrap method is superior to the product-distribution method, which is superior to the Sobel test, in which the bias-corrected percentile Bootstrap method provides the most accurate estimate of confidence intervals and has the highest statistical efficacy [44].Specifically, the Bootstrap method obtains Bootstrap confidence interval estimates for ab by continuously drawing Bootstrap samples and calculating estimates of a and b.If the interval estimate does not include zero, the mediation effect is significant; if the interval estimate includes zero, the mediation effect does not exist [45].The results of the mediated effects showed (see Table 5) that the Bootstrap 95% confidence intervals for the total indirect effects arising from physical activity and subjective well-being did not include a value of 0 (BootLLCI = 0.426, BootULCI = 0.578), suggesting that cognitive reappraisal and resilience mediated significant effects between physical activity and subjective well-being, with a total indirect effect size of 0.398, accounting for 79.28% of the total effect; further analysis shows that this total indirect effect includes three mediating effects: indirect effect 1: physical activity → cognitive reappraisal → subjective well-being, with confidence intervals that do not include a value of 0 (BootLLCI = 0.028, BootULCI = 0.080), indicating a significant indirect effect of this pathway, with a mediation-effect size of 0.052, accounting for 10.36% of the total effect; indirect effect 2: physical activity → resilience → SUBJECTIVE SENSE OF HAPPINESS, with a confidence interval that does not contain 0 (BootLLCI = 0.231, BootULCI = 0.345), suggesting that this pathway is significant in terms of its indirect effect with a mediation-effect size of 0.285, accounting for 56.77% of the total effect; indirect effect 3: physical activity → cognitive reappraisal → resilience → subjective well-being, with a confidence interval that does not contain 0 (BootLLCI = 0.046, BootULCI = 0.083), suggesting that this pathway has a significant indirect effect, with a mediation-effect size of 0.062, accounting for 12.35% of the total effect.In summary, the chain-mediation effect of cognitive reappraisal and resilience in physical activity affecting university students' subjective well-being is significant.Therefore, this study's Hypotheses 1, 2, 3 and 4 were verified.Note: BootLLCI refers to the lower limit of the Bootstrap-sampling 95 per cent interval, and BootULCI refers to the upper limit of the Bootstrap-sampling 95 per cent interval.

Differences in the Subjective Well-Being of Different Groups of University Students
Subjective well-being is a special subjective feeling of people closely related to individuals' specific situations.The study results show that the subjective well-being of different groups of university students varies.Specifically, there is no significant difference in the perceived subjective well-being of university students by gender and region, which suggests that gender and region do not have a differential impact on the subjective well-being of university students.The non-significant gender difference differs from existing related studies [17].The reason for the non-significant gender difference may be that this study analyses total subjective well-being, and men and women are relatively close to each other in total subjective well-being, which does not result in a significant difference.The insignificant regional differences may be because the surveyed regions and universities may have similar environments, and similar environmental influences between different regions are not enough to cause differences in the subjective well-being of university students.There are significant differences between the university student groups regarding age, education, and sports level, indicating that different ages, education, and sports levels can have differential effects on university students' subjective well-being.The reason for the significant difference in subjective well-being among university students of different ages and educational levels is easy to understand, because university students with higher ages and educational levels have better life experience, rich knowledge reserves and are more likely to feel warmth and goodwill from the outside world, and are also able to satisfy themselves quickly, which helps them to obtain higher subjective well-being.There are significant differences among university students with different exercise levels, possibly due to the exercise benefits brought by different exercise levels and the differences in exercise intensity, frequency, and time at different exercise levels [46].Compared to the lack of benefits at low levels of exercise and the over-commitment at high levels of exercise, moderate levels of exercise brought the best subjective well-being to university students, which is consistent with the results of the previous study [47].The perceived subjective well-being of different groups of university students varies, which reminds us that we need Behav.Sci.2024, 14, 164 10 of 15 to take targeted measures according to the age, education, and sports level of university students to improve their subjective well-being effectively.

The Influence of Physical Activity on the Subjective Well-Being of University Students
Physical activity is a kind of activity that improves physical and mental health through certain intensities, frequencies and durations.The study results showed that physical activity has a significant positive effect on the subjective well-being of university students, and research Hypothesis 1 was verified, which is consistent with the results of existing studies [48].Regular physical activity can encourage individuals to produce more positive emotions and states of mind.It has reached a certain degree of consensus in the field of physical education, and this kind of promotion has a certain relationship with the individual's gender, age, race and other factors and even has a certain relationship with previous experiences of physical activity.However, it is essential to note that different intensities and durations of physical activity can produce different effects.In contrast, moderate-intensity physical activity is the most effective in enhancing university students' subjective well-being, while high-intensity physical activity does not achieve the effect of facilitation but may inhibit and resist the positive emotions of university students [5,49].In addition, from a cognitive-neurological point of view, positive physical activity can also promote the production and release of endorphins, reduce adrenaline and cortisol activities and significantly reduce negative emotions such as depression, sadness and dissatisfaction, which can effectively enhance the subjective well-being of university students [50].Of course, there are many other ways for physical activity to enhance the subjective well-being of university students, such as collective physical activity by improving peer relationships, deepening friendship among peers, improving individual social relationships and social adaptability, and then making university students physically and mentally satisfied and happy.Physical activity also creates a natural social platform for university students, enabling them to integrate into the group and form a good social network, generating a sense of belonging to the school, promoting positive emotions, and improving school-life satisfaction.In conclusion, scientific and practical physical activity can enhance university students' subjective well-being in many ways.

The Mediating Role of Cognitive Reappraisal
The study results show a significant positive correlation between physical activity, cognitive reappraisal and university students' subjective well-being, and cognitive reappraisal has a mediating role in the mechanism of physical activity affecting university students' subjective well-being, and research Hypothesis 2 has been verified.Cognitive reappraisal can mediate the relationship between physical activity and subjective well-being, which is consistent with previous studies' main findings [40].Appropriate physical activity can help university students alleviate anxiety, release stress, and enjoy themselves physically and mentally.However, physical activity itself is also a special kind of stressful event, mainly medium-and high-intensity exercise, which can cause an increase in an individual's cortisol response, so in the process of physical activity, individuals need to constantly fight against instinctive reactions and their instinctive responses and find a balance between avoidance and perseverance by re-evaluating the health beliefs and other autonomous motivations [22].Because of this, university students who regularly engage in physical activity are more likely to use cognitive reappraisal strategies to cope with stressful events in their lives and studies.Cognitive reappraisal, as an essential emotion-regulation strategy, alters an individual's understanding of an emotional event, reducing the individual's emotional induction.Thus, cognitive reappraisal often predicts the possibility of more positive emotions and states of mind.In addition, the ability of physical activity to influence university students' subjective well-being is also inextricably linked to its ability to optimise emotion regulation.Cognitive reappraisal effectively reduces negative emotional experiences, physiological responses, sympathetic nervous system activation and activation levels in the amygdala and medial orbitofrontal cortex [51].When university students are accus-tomed to using cognitive reappraisal strategies to cope with emotional events, it means that the positive emotional experience increases and the positive emotional experience can expand the attention and cognition of university students, promoting university students to effectively cope with problems and construct various resources, which is essential for the maintenance of high levels of subjective well-being for university students.

The Mediating Role of Resilience
The study showed a significant positive correlation between physical activity, resilience and subjective well-being among university students and that resilience has a mediating role in the mechanism by which physical activity affects university students' subjective wellbeing.Study Hypothesis 3 has been verified, which is also consistent with the main findings of the existing related studies [52].The developmental model of psychological resilience suggests that stress of appropriate intensity is a psychological challenge to the individual, but stress can also enhance psychological resilience when overcome.Positive physical activity can provide the appropriate space and conditions for the development of resilience in university students, which can positively affect their resilience [53].For example, in participating in physical activity and competitions, university students may encounter the pressure of sports training, the challenge of athletic competition, and the frustration of losing the competition, which may temporarily impact the positive mental state and emotions of university students.However, after actively coping with and overcoming these difficulties, university students can form a more stress-resistant and resilient state of mind, which can help them to effectively cope with and adapt to adverse stress events when facing similar situations again in the future and maintain a more positive attitude towards life and their emotional states.In addition, university students with higher psychological resilience can use multiple problem-solving strategies to alleviate the adverse effects of stressful events in physical activity, maintain their psychological health, and have less anxiety and depression when facing problems [54].In general, students with higher resilience are less likely to experience anxiety and depression.In general, university students with higher resilience have an optimistic and enthusiastic attitude toward life, are curious and open to new experiences, and can cope with current challenges in physical activity with abundant energy and highly positive emotions, thereby gaining a subjective sense of well-being.Therefore, resilience, whether under adversity or less stressful conditions, enables university students to be optimistic, cheerful and energetic in physical activity and maintains and enhances subjective well-being.

Chain-Intermediation-Modelling Analysis
The Bootstrap method verified the chain-mediating role of cognitive reappraisal and resilience in the positive effect of physical activity on subjective well-being, and research Hypothesis 4 was validated.The construction of the chain-mediation model provides a new perspective to advance further and understand the relationship between physical activity and subjective well-being among university students.On the one hand, physical activity can promote cognitive development by strengthening the body and mind, using physical experience to enhance university students' subjective well-being.Cognitive reappraisal is a vital emotion-regulation strategy.However, it belongs to prerequisite-focused emotion regulation, re-processing the causes of emotions.It mobilises more of one's cognitive processing system to reappraise the explanations of the causes of emotions and changes one's understanding of emotional events [54].When there are more positive than negative emotions in daily life, it can lead to a more positive evaluation of one's quality of life and, thus, provide a greater sense of perceived well-being.Physical health and mental wellbeing are the foundations of a happy life.From an embodied perspective, physical activity is essential for promoting physical health and mental fitness.In addition, an important protective factor of psychological resilience is rational cognition, and university students use cognitive-reappraisal strategies to reconstruct their situation and state of mind, which is conducive to the development of psychological resilience and improves the ability to adapt to stress, which in turn can lead to the perception of more happiness.On the other hand, positive physical activity can build up psychological energy and enhance resistance to frustration and stress, affecting university students' subjective well-being.Sampedro-Piquero et al. (2021) explained that physical activity can regulate the gene FKBP5, a potent inhibitor of the glucocorticoid receptor and an essential regulator of the stress response [55].University students with higher levels of resilience can successfully cope with adversity and stress in their lives and have fewer stress reactions, making them more likely to perceive subjective well-being.

Conclusions
This study explored the influence mechanism of physical activity on university students' subjective well-being and the mediating roles of cognitive reappraisal and resilience through the chain-mediation model, and the following conclusions can be obtained: (1) physical activity, cognitive reappraisal and resilience can all enhance university students' subjective well-being; and (2) physical activity can directly affect university students' subjective well-being and can indirectly affect university students' subjective well-being through the mediating role of cognitive reappraisal and resilience.There are four specific paths, including the direct role: physical activity → subjective well-being; intermediary role 1: physical activity → cognitive reappraisal → subjective well-being; intermediary role 2: physical activity → resilience → subjective well-being; chain-intermediary role: physical activity → cognitive reappraisal → resilience → subjective well-being.→ cognitive reappraisal → resilience → subjective well-being.To sum up, positive physical activity enhances the internal mechanism of the subjective well-being of university students: regular physical activity can promote the cognitive development of university students, accumulate psychological energy, and then enable university students to effectively cope with and adapt to various frustrations and pressures in their lives and studies, maintain a stable state of mind, and ultimately help university students to perceive more happiness.

Research Limitations and Future Research Directions
Although the study has considered many interfering factors and avoided some limitations as much as possible, there are still some shortcomings and limitations.Firstly, due to time constraints, limited research funds and other objective factors, this study mainly collected data through self-administered scales, which may be relatively singlular and have certain limitations in research methodology, and semi-structured interviews and case studies can be added in the future to further improve the scientific nature of the research results.Secondly, this study mainly explores the effects of physical activity on university students' subjective well-being from an overall perspective.It does not separately explore the effects of exercise intensity, time and frequency on university students' subjective wellbeing, which can be further increased to increase the impact of exercise intensity, time and frequency on their subjective well-being.Finally, this study mainly reveals the effect of physical activity on university students' subjective well-being on a theoretical level.In the future, it can be demonstrated that physical activity positively affects university students' subjective well-being from the perspective of events through intervention experiments.

Table 1 .
Specifics of the valid sample.

Table 2 .
Correlation analysis between core variables.

Table 3 .
Differential test of subjective well-being of different groups of university students.

Table 4 .
Regression analyses of chained mediation effects for cognitive reappraisal and resilience.

Table 5 .
Bootstrap analysis for mediation-effect test.